1. Technical Field
The present disclosure relates to lens actuators, and particularly to a voice coil motor having positioning holes and corresponding positioning sockets configured for cooperatively receiving positioning members.
2. Description of Related Art
Generally, lens modules employ an actuator such as a voice coil motor to move a lens barrel (containing at least one lens) relative to an image sensor, thereby varying a distance between the lens(es) and the image sensor to obtain a desired focal length.
A typical voice coil motor includes a barrel holder for accommodating a lens barrel, a coil wrapped around the barrel holder, a plurality of magnets, a bracket bearing the magnets and accommodating the barrel holder, and a resilient plate interconnecting the bracket and the barrel holder for holding the barrel holder on the bracket. When an electric current is applied to the coil, a magnetic force is produced between the magnets and the coil, and the barrel holder with the lens barrel is moved relative to the magnets. When the electric current is cut off, the barrel holder with the lens barrel is reset to its original position under a resilient force applied by the resilient plate.
During assembly of the lens module, the resilient plate is attached on an end surface of the bracket, and the barrel holder is accommodated in the bracket with an end of the barrel holder connected with a resilient portion of the resilient plate. Then an external torque is applied on an end of the lens barrel to screw the lens barrel into the barrel holder until the lens or lenses inside the lens barrel arrive(s) at the optimum focal plane. Accordingly, the resilient plate simultaneously bears a horizontal friction force and the torque transmitted from the barrel holder. The friction force keeps the resilient plate still. If the values of the friction force and the torque exceed the maximum values the resilient plate can bear, the resilient plate is inevitably distorted or damaged.
Therefore, what is needed is a voice coil motor to overcome the problems described above.